1. Field of the Invention
The present invention relates to a next generation mobile communication system, and more particularly, to in a method for controlling a radio access bearer in a next generation mobile communication system.
2. Background of the Related Art
Recently, the Association of Radio Industries and Business (ARIB) in Japan, the European Telecommunications Standards Institute (ETSI) in Europe, the TI in the USA, the Telecommunications Technology Association (TTA) in Korea, and the TTC in Japan have planned a further evolved next generation mobile communication system based both on the core network technology of the existing Global System for Mobile Communications (GSM) which serves for multimedia, such as audio, video and data, and radio access technology. These organizations have agreed on common research for suggesting a technical specification for the evolved next generation mobile communication system, a project named Third Generation Partnership Project (3GPP). The 3GPP encompasses the following three technical research fields.
The first technical research field is the 3GPP system and service field, for researching system architectures and service capabilities based on the 3GPP specification.
The second technical research field is the field of Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is a RAN (Radio Access Network), including W-CDMA according to a Frequency Division Duplex (FDD) mode, and TD-CDMA according to a Time Division Duplex (TDD) mode.
The third technical research field pertains to a core network having a third generation networking capability, such as mobility management and global roaming, being evolved from the second generation GSM.
Of the Technical Specification Groups (TSGs) conducting such technical research, the Working Group 1 (WG1) related to Radio Access Networks (RAN) suggests general technologies for the physical layer (Layer 1), and the Working Group 2 (WG2), defines a data link layer (Layer 2) and a network layer (Layer 3), both being at higher levels than the physical layer, as a second radio layer (Radio Layer 2) and a third radio layer (Radio Layer 3), and suggests general technologies on the second and third radio layers.
FIG. 1 illustrates a related art radio interface protocol architecture according to the 3GPP RAN. An air-interface protocol between UE (User Equipment) and a network side (UMTS Terrestrial Radio Access Network, UTRAN) consists of layer 1, radio layer 2, and radio layer 3.
Referring to FIG. 1, a protocol architecture is divided into a control plane (C-Plane) for signaling, and a user plane (U-Plane) for transmission of information. The C-Plane has a Radio Resource Control (RRC) Layer at Layer 3, and a Radio Link Control (RLC) Layer and a Medium Access Control (MAC) Layer at Layer 2, a layer lower than the Layer 3, and a Layer 1 at a lowest layer. The U-Plane has the RLC and MAC at Layer 2, and the Layer 1, a layer lower than the Layer 2. The Layer 1 provides a transport channel for upper layer(s) inclusive of the MAC. In this instance, depending on how information is transferred on the air-interface, different transport channels are provided, i.e., either a common transport channel or a dedicated transport channel is provided.
The MAC provides the upper RLC with logical channels, which differ depending on the forms of information to be transported. That is, the MAC provides the data transfer service on the logical channels, forms of which logical channels differ depending on the kinds of the data transfer services provided by the MAC. In this instance, the forms of the logical channels differ depending on the forms of information to be transported, wherein, in general, control channels are provided when information for the C-Plane is to be transported, and traffic channels are provided when information for the U-Plane is to be transported. Besides this, the MAC provides radio resource reconfiguration and MAC parameter reconfiguration services, which are served when the RRC requests a radio resource reconfiguration or a MAC parameter change. The MAC also provides a measurement report service, reporting traffic volume values, a service quality index, a MAC condition index, and the like to the RRC. The MAC providing those services has many functions, including a traffic volume monitoring function which informs the RRC of the traffic volume on the logical channel. The RRC analyses traffic volume information reported from the MAC, and determines switching for the transport channels.
The RLC provides services for radio access establishment/or cancellation. The RLC also provides a service for transporting PDU (Protocol Data Units) at the upper layer to which any protocol information, inclusive of segmentation/reassembly functions, is not included. The RRC provides an information broadcast service, in which information is broadcast to all UE in an one area. The RRC also controls Layer 3 C-Plane signal processing between the UE and the UTRAN. That is, the RRC provides functions of establishment, sustenance, and cancellation of radio resource access between the UE and the UTRAN. Particularly, the RRC provides functions of establishment, sustenance, or cancellation of radio access bearers, functions of assignment, reconfiguration, and cancellation of radio resources required for radio resource access (the bearer is a capability defined for a signal transfer on the radio interface), and UE measurement report and report control functions, corresponding to the traffic volume monitoring function among the functions of the MAC. The measurements at the UE are controlled by the RRC, when the RRC informs the UE of an object, a time and a method of the measurement. Then, the RRC informs the UTRAN of the measurements at the UE. The radio interface protocol layers explained up to now provide other various functions and services. In such an existing radio interface protocol architecture, traffic volume at the RLC is monitored at the MAC in the U-Plane, for the RRC to assign, sustain or cancel radio resources.
However, no detailed procedures for these functions are suggested yet, in fact. That is, as explained, what is described in the 3GPP RAN is only that a RLC traffic volume in a current user system is monitored at the MAC, and only that radio access bearer control procedures, such as bearer reconfiguration, and channel reconfiguration are carried out according to the traffic volume monitoring at the MAC, without any suggestions for detailed procedures for carrying this out.